Extensor Pollicis Brevis
Hand
Forms the other border of the anatomical snuffbox — and is involved in De Quervain's tenosynovitis.
Function
Extends MCP joint of thumb, assists in wrist abduction
Origin
Posterior radius and interosseous membrane
Insertion
Base of proximal phalanx of thumb
Innervation
Posterior interosseous nerve (C7-C8)